#include <iostream>
using namespace std;
int main(){
    char op[5]; cin >> op;
    double sum = 0.0;
    for(int i = 0; i < 12; i ++ ){
        for(int j = 0; j < 12; j ++ ){
            double tmp; cin >> tmp;
            if(i > j)   sum += tmp;
        }
    }
    if(op[0] == 'M')    sum /= (12 * 11 / 2);
    printf("%.1lf", sum);
    return 0;
}